1. Field of the Invention
The invention relates to an ink jet print head, in particular an ink jet print head comprising a piezoelectric actuator. In particular, the invention relates to an ink jet print head, in which a piezoelectric actuator is arranged to be used in a deflection mode for deflecting an actuator membrane in order to pressurize ink in a pressure generation chamber.
2. Description of Background Art
U.S. Pat. No. 7,101,026 B2 describes different types of ink jet recording heads. A piezoelectric element is placed on one side of a flow passage formation substrate via a diaphragm and has a lower electrode, a piezoelectric layer and an upper electrode. At least one of the layers deposited under or on top of the piezoelectric layer is a compression film having a compressive stress, and the compression film has at least a part in a thickness direction removed in at least a part of an area opposed to a pressure generation chamber, whereby the stress of the whole film is decreased. In one example, the diaphragm is made up of an elastic film and a lower electrode film, on top of which a piezoelectric film and an upper electrode film are patterned. The material of the upper electrode film has a compressive stress in an opposite direction to a stress of the piezoelectric film.
US 2006/0158486 A1 describes a printhead module having a piezoelectric actuator positioned over a pumping chamber and configured to deflect and pressurize the pumping chamber. A ground electrode layer is deposited on a nozzle plate. A piezoelectric layer is metallised on one surface with a layer of Titanium-Tungsten, and the metal layer is bonded and electrically connected to the metallic ground electrode layer. A silicon handle layer is removed on the other side of the piezoelectric layer. A metal layer forming a drive electrode is disposed on the exposed surface of the piezoelectric layer by sputtering layers of metal, e.g. Titanium-Tungsten and/or gold.
WO 2009/143354 A2 describes an ink jet printhead having a multi-layered actuator bonded onto a membrane, such as a layer of silicon. The actuator includes a lower conductive layer, a piezoelectric layer and an upper conductive layer. The upper conductive layer provides an upper electrode. The piezoelectric layer, which is metallised with a metal that forms the lower conductive layer, is bonded onto the membrane. Alternatively, the piezoelectric layer is formed directly on the lower conductive layer. In one example, the upper conductive layer includes a Titanium-Tungsten alloy layer and a gold layer.
WO 2006/009941 A2 deals with an ink jet print head module having a piezoelectric element stiffened by a curved surface. The stiffened piezoelectric element is prepared by grinding a curved surface into a thin layer of piezo-electric material or by injection molding a precursor into a mold having the curved surface features of the piezoelectric element.